The present invention relates generally to systems for detecting the presence of humans in an area and, more specifically, to such systems for determining whether the humans in the area are observing an installation, artifact or person.
There are many electronic and optical devices and systems currently available for allowing the observation of persons without the observee's knowledge or consent. Many of such devices and systems allow such observation at night or in an area of low illumination or at such a great distance that the observee could not easily see or otherwise be aware of such observation. In addition, such devices and systems are not uncommonly used in conjunction with eavesdropping devices which allow monitoring of confidential communications in addition to identification of the persons making the communications and observance of their behavior. The sophistication of such devices and systems has increased markedly, and this has facilitated their cryptic and effective use. However, many people view the proliferation of such devices and systems as an assault on the privacy of individuals. In addition, the effectiveness and ease of use of such devices and systems has made it harder to preserve the secrecy of governmental installations and the programs conducted therein as well as industrial plants and buidings which may be utilizing trade secrets in their manufacturing processes. In fields of business in which a competitive edge may be all important to the success of a business, the vulnerability of business processes and practices which utilize trade secrets to surveillance may result in the untimely failure of such businesses. Many private individuals may also find themselves vulnerable in their personal, professional and business lives by use of such devices and systems in surveillance of their homes, offices, etc. Moreover, many people may be psychologically harmed, emotionally distressed or simply feel ill at ease by the thought or belief that persons unknown may be watching them. In this regard, much of the unauthorized surveillance or observation that takes place is conducted by persons who may be on public property or otherwise not in a location in which their presence may violate the law. Consequently, such surveillance may not be easily prevented. However, such surveillance may be actionable under law if its nature or existence can be established.
Although many devices and systems to aid in unauthorized surveillance or observation are commonly available, far fewer devices and systems are available to detect the existence of and determine the nature of such surveillance or observation. Consequently, what is needed is a system to detect the presence of an observer, to determine generally what is being observed and to perform such detection at a moderate distance from the observer.